Regulation of the combustible mixture for internal-combustion engines



Oct. 23, 1945. P. LORANGE 387,2??? REGULATION OF THE COMBUSTIBLE MIXTUREFOR INTERNAL-COMBUSTION ENGINES Flled Oct 19' 1938 '4 Sheets-Sheet 1Oct. 23, 1945.

7 N 0 P g P. LORANGE REGULATION OF THE COMBUSTIBLE MIXTURE FORINTERNAL-COMBUSTION ENGINES Filed 061;. 19, 1938 4 Sheets-Sheet 2 Oct.23,1945. E 2,387,277

REGULATION OF THE COMBUSTIBLE MIXTURE FOR INTERNAL-COMBUSTION ENGINESFiled Oct. 19, 1958 4 Sheets-Sheet 3 3 2 w a u g; a: u L

' o 3040 so 00- Horse Power- Km er Hour P. LORANGE 7 ,387,277

REGULATION OF THE COMBUSTIBLE MIXTURE FOR 1 INTERNAL-COMBUSTION ENGINESFiled 001;. 19, 1938 v 4 Sheets-Sheet 4 Patented Oct. 23., 1

REGULATION OF 2,387,271 THE COMBUSTIBLE. MIX- TURE FORINTERNAL-COMBUSTION EN- GINES Prcsper LOrange, Stuttgart-Feuerbach, Ger-I many; vested in the Alien'Property Custodian Application October 19,1938, Serial No. 235,881

, Germany March 2, 1936 9 Claims. (G. 123-139) This invention relates toapparatus forthe regulation of the combustible mixture for internalcombustion engines. l The formation of the combustible mixture ininternal combustion engines by means of carburettors has the advantagethat the quantity .of fuel is proportioned directly to the quantity ofair supplied, but suffers on the other hand from the drawbacks that thefuel has a free surface in the carburettor, that the carburettor issensitive to position, and that the mixture is liable to be too rich athigh speeds. The fuel pressures produced are also too low to effectsuflicient atomisation, particularly if the fuel is in- Jected directlyinto the interior of the cylinder in contrast to injecting it into aninduction pipe leading thereto.

With a view to retaining the above-mentioned advantages whilst avoidingthe disadvantages it has been proposed to employ fuel pumps designed togive-a variable supply and regulated by means of apparatus influenced bythe pressure of the air 1n the induction pipe of the engine. Suchregulation cannot, however, be carried out sufliciently simply andsensitively.

According to the present invention, means for.

supplying fuel and air to an internal combustlon engine, comprisesincombination an air passage along which the air flows in the operationof the engine; at'least one injection nozzle for the fuel, adapted "todeliver a charge thereof into the air, to be burnt in the engine; pumpmeans arranged to supply fuel to the injection nozzle at a rate which isin excessof the rate at which the fuel is delivered fromthe nozzle;

derived from the motion of the air along the air passage and theresultant of which is directly proportional in magnitude to the rate offlow of said air, the pressures on the two sides respectively of thecontrol member forming the pressure differ-- ential thereon beingcommunicated to the memher from the air flowing along the passage.

In carrying the invention into effect the pressuredifierential derivedfrom the motion of the air in the air passage may be caused to acteither directly upon, or by producing a partial vacuum upon, a piston ora diaphragm surface so arranged that the force acting thereon influencesthe loading of the control valve (hereinafter referred to as theoverflow valve) in the fuel pipe by which fuel is supplied to aninjection nozzle or proportion to the quantity of air drawn into the]engine per unit of time, but the air pressure thereby produced increasesas the square of the speed of flow. Consequently, the load on the anautomatic two-way control-valve interposed between the pump means andthe injection nozzle and connected to these parts by pipelines in such amanner that the excess quantity of fuel dehvered by the pump means isreturned theretoby way of the valve, which valve comprises a movablevalve element, the position of which in the valve determines themagnitude of excess of fuel that is-returned to the pump and'correspondingly the quantity of fuel that is delivered from the nozzle;and loading means for the valve, adapted to load the same and therebyadjust the position of the valve element therein in accordance atallengine speeds and corresponding rates of flow of air along the airpassage, with the rate of flow of said air, the -saiclioadingmeans'comprising for this purpose a control member for the valve elementwhich is movable, with consequent corresponding movement of the valveelement, under the effect of a pressure differential upon it overflowvalve, and therefore the pressure-in the fuel supply pipe, increases asthe square of the air speed. The injection velocity of the fuel,however, corresponds to the square root of the pressure of the supplythereof and thus is proportional to the speed of flow. of the air.

.The regulation of the mixture in accordance with the invention can beeffected whilst using either pumps with a uniform rate of delivery, for

example, gearpumps, or piston pumps having a separate piston foreachnozzle tobe supplied. In the first case, a decisive factor in thedesign is whether a carburettor delivering a uniform flow Y of mixtureto a plurality of cylinders is to he replaced, or whether the fuel isto'be delivered to valve is necessary for all the pumps. In the SEC? ondcase, no control of the injection valves need take place if a separateoverflow valve is p 1 vided for each nozzle. On the other hand, if it'isdesired to use a multiple cylinder pump with only one overflow valve,control of the injection valves is necessary. Sucha-control isfrequently diflicult to provide for, however, particularly when theinvention is to be applied to existing'types of engines. I v

According to a further feature of the invention,

therefore, when a multiple piston pump is employed with only oneoverflow valve, the control at the injection nozzles is effected by'thepump In order to efiect such control in a simple manner the piston ofeach pumping unit is utilised to control the communication between apump delivery space common to all the pumping units, and

a nozzle corresponding to the said piston. In this case a given pistondoes not operate to convey the charge delivered thereby to thecorresponding nozzle, =but actuates a control member which establishes aconnection between the nozzle and the pump delivery space into which allthe pumping units deliver, so that on the one handa portion of thedischarge of the other pumping units passes through the opened nozzleand, on the other hand, the total discharge of the piston actuallyoperating does not pass through the said nozzle.

The quantity of fuel supplied through an open nozzle is determined bythe regulated pressure common to all the pump delivery spaces and by airflowing per unit of time. 1

Thus, according to one constructional embodimerit of the invention aconstriction may be provided in the suction pipe, for example by meansof a so-called Venturi tube, and a connection made between the positiontherein at which the air has its maxlmumvelocity and lowest pressure andthe lower side of a piston or diaphragm regulating the overflow valve,the upper side of which piston is exposed to the pressure of the air inthe suction pipe before reaching the constriction.

The overflow valve is thus loaded by a resultant pressure which, ifnecessary, may be increased by the pressure of a spring for the purposeshereafter described; the valve will therefore open as soon as thepressure of the liquid multiplied by the cross-section of the valve isgreater than the resultant pressure acting on the regulating pistonmultiplied by the cross-section of the latter, plus the force of thespring.

The pressure of the liquid thus always remains proportional to thedifference of pressure of the flowing air at the two points in thesuction pipe to which the valve regulating device is conneci:

' and this ratio can easily be made very large, as

.otherdeflection surface, by which the current of air is deflected.

Such an arrangement can readily be so formed that there is noconsiderable loss of air velocity. It can also be conveniently designedto oscillate about a pivot and be made to act upon the overflow valvethrough a transmission mechanism.

The injection nozzle, when it is controlled, can be closed by a valveopening inwardly or outwardly. When the nozzle is not controlled it can,particularly when the injection takes place in the cylinder, beclosed-by an outwardly opening needle' or by a spring-loaded check valveopening inwardly. The nozzle, however, can also be quite open,especially when it discharges into the suction pipe leading to theinletvalve.

If a controlled injection nozzle is used in conjunction with a pumphaving a uniform output,

the control may be effectedby means of a me-- chanical'controlderived-from the cam shaft, and conveniently from the existing controlof the inlet valve. 4

In addition to effecting a, control of the fuel supply in the manneralready described it may I beneoessary or desirable to effect acorrection of the richness of the mixture, the nature of the correctiondepending upon the particular circumstances or requirements, and furtherfeatures of the invention are concerned with such corrections. Thus itis sometimes found that the quantity of fuel at higher engine speedsbecomes too great as a consequence of the air attenuation then takingplace, so that the mixture becomes too rich. In order to obviate thisdifficulty according to a further feature of the invention, the overflowvalve, in addition to being loaded in accordance with the pressure ofthe airflow, is also loaded with an approximately constant additionalforce, for example by means'of a spring. It is ing-upon the pressure ofthe air flow, and supplied, for example, by a spring the tension ofwhich is varied with the load. For this purpose the tension of thespring may be varied simultaneously with the adjustment of the throttleregulating the output, so that an additional initial tension is impartedto the spring when the throttle is slightly open and when it is fullyopen, but the tension is relieved in the intermediate position of thethrottle corresponding for exampie, to the stage between sixty per centand eighty per cent of the full load.

In still other cases, notably in the case of heavy motor vehicles, itmay be desired that the mixture should be particularly rich at a certainspeed, for example at the speed at which gear-changing takes place, andshould become weaker with increasing speed. In such cases, according toanother feature of the invention, the fuel curve is corrected forexample, by employing the inertia of a centrifugal regulator, by loadingthe overflow valve with a force, additional to that depending upon thepressure of the air flow, which is influenced by the speed and increasesor decreases therewith. In this way, a mixture can be produced which isricher at low speed and at maximum speed, but poor at intermediatespeeds, or which is richest at any given speed.

. Another feature of the invention relates to the plied, and providedthat the density of the air remains constant. The proportions of themixture would not, however, remain constant with v variations inthealtitude at which the engine is operating, since, although the fuelpressure is reduced in direct proportion to the fall in air density, thequantity of fuel supplied per unit of time varies as the square root ofthe air density.

invention, this fault is corrected by reducing thewe force loading theoverflow valve as the altitude j increases. This may be effected byapplying an additional force having a negative action, the said I forcebeing'provided, for example, by a diaphragm chamber, filled with air atnormal atmospheric pressure so as to expand as the altitude increases,and arranged to reduce the load on the overflow valve when such increasetakes place. If a supercharging blower is provided, the differencebetween .the blower pressure and the external pressure may be employedto produce the variation in loading of the overflow valve, the saiddifference in pressure being compensated for by a spring as is morefully. described hereafter.

In order that the invention may be clearly understood and readilycarried into effect reference will now be made to the accompanyingdrawings,

in which Figure 1 illustrates diagrammatically an engine having a fuelsupply installation according to the invention which embodies controlledinjection nozzles and a fuel supply pump with a uniform output;

Figure 2 illustrates an arrangement for conconjunction with anintermittently discharging piston pump;

Figure 4 illustrates a modification of the invention in which severalinjection nozzles are supplied separately from the pumping units of amultiple piston pump and the operation of the nozzles is controlled bythe pump pistons;

est point of which a connection is made with the underside of aregulating piston j which works in a cylinder 0 and is thus subjected onits-underside to the reduced pressure resulting from the partial vacuumat the point cin the pipe 1).. The upper end of the cylinder e isconnected to the pipe at a point on the inlet side of the constrictionc. The piston I is thus loaded in accordance with the difierence in thepressures in the pipe b at the point e and on the inlet side thereof. Inad- 1 dition the piston j is loaded by a spring 9 for effecting acorrection of the fuel delivery. curve in a manner more fully describedhereafter in connection with Figure 6 of the drawings. These loads areapplied to the overflowvalve h which is made as a needle and closes thepipe is from The manner in which this construction operates isillustrated in Figure 6 of the drawings, in which the full linecurve A,B illustrates the increase of the fuel pressure p with the engine andair supply speeds, at aconstant position of the air throttle. By takingthe square roots of the values for the pressure p given-by the curve A,

B, a curve E, F corresponding to the fuel in- :Iection velocity v is,obtalnedl This curve, as can be seen, is in the form of a straight line,indicating that the fuel injection velocity increases Droportionally tothe engine speed.

Figure 2 illustrates one manner of controlling the injection valves dillustrated in Figure 1. In this construction, the valve is moved by thelever .o of thecylinder inlet valve, so that it is open during the wholeor a portion of the suction period. By shifting a collar s, the periodof-oper ing and the height of the opening movement of the valve d can beadjusted. The injection valve could equally well be controlled directlyfrom the cam shaft t by means of cams and double armed levers. "Theadjustment of the valve during working (for example, to obtain a weak ora rich mixture) could then take place, for example, by ad- 'Figure 5illustrates in detail a construction of V a pumping unit andinjection-valve control suitable for use in the embodiment illustratedin Figure 4.

of a fuel supply installation constructed in accordance with theinvention, and one way in which the mixture proportions may becorrected. Figure 7 to 10 are further diagrams illustrating thecorrection of the mixture proportions to take account of difierentcircumstances and conditions, and Figures l1, 12, 13 and 14 illustratevarious modifications of an apparatus constructed according to theinvention, designed to eiiecttho corrections illustrated respectively inFigures 7. 8, 9 and 10.

Referring to the construction illustrated in Fig ure 1 of the drawings,the four controlled injection valves d of an engine a are supplied withfuel from a pump 1 having a uniform rate of delivery, by means of a pipen connected in parallel with the four injection valves (1. The pipe 11is connected to an overflow pipe k. controlled by an overflow valve h,and leading to the supply tank and thence back to the suction side ofthe pump Z. There is inserted in the air. suction pipe b of the engine aa constriction c from the narrowlusting the lever fulcrum which in thiscase would be eccentric.

In the modification illustrated in Figure 3, the

during the corresponding suction stroke, so that there arises in thepassage n a pressure propor tional to the square of the air velocity.When the pressure of the fuel exceeds this .value the valve portionthereof that the current of air deflected by the blade. 21 is caused tofollow an S-shaped path. v

In usefthe pump is so adjusted as to commence its delivery strokeshortly after the com- A spring g is provided in this case also to'efiect a correction of the fuel delivery curve as described hereafterwith reference to Figure 6.

The rebound surface it may also be made round and act directly on theneedle 72..

The nozzle opening may also be closed by an automatic valve, especiallywhen theinjection takes place in the cylinder itself.

In addition to effecting the correction described with reference toFigure 6, the spring g may be used to provide a supplementary load inorder to compensate for a constant resistance in the injection pipe n orthe nozzle (1, for example, the resistance of a spring-loaded valvetherein. The fuel'pressure necessary for the opening of such a valvewould then be determined by the spring g which would have to be'designed to provide a force corresponding to that pressure, in additionto the force required for effecting the correction of the mixtureproportions.

In the modification illustrated in Figure 4 the air suction pipe 11 of asix-cylinder engine a is connected to a regulating device e, for exam--ple of the form illustrated in Figure 1. The pressure of the fuel supplyto the injection nozzles is produced by a multiple piston pump G, allthe units of which discharge into the same delivery space D which isconnected by a pipe is to the overflow valve of the device e. Thepressure in the delivery space of the pump G is thus kept at a levelcorresponding to'the square of the quantity of air supplied per unit oftime. The outflow of the excess fuel from the device 6 takes placethrough the pipe Eto-the pump suction pipe m.

The pistons L of the pump G are so" adjusted that each piston reachesthe end of its discharge stroke approximately at the mid point of thein- Jection period of the corresponding injection valve.

During th compression stroke of a given piston L a pressure valve Hopens, but the stroke of the said valve H is limited by avalve J, whichis-held on its seat by a strong spring. At the end of the compressionstroke, however, the piston L positively engages the valve H and thuslifts it and the valve J by a small amount, so

that during this period the pressure space D is connected to the pipe I(or II, III, IV, V,or VI as the case may be) supplying the left hand endinjection nozzle :1.

The construction of one of the pumping units diagrammaticallyillustratedin Figure 4 is more clearly illustrated in Figure 5. In thisconstruction the pump housing G contains a piston guide K in which thepiston L slides. In the position shown, the piston L is at the upper endof its stroke and has lifted, by means of an extension 8. the pumpdischarge valve H and with it the control valve J, so that the passagein the union- R is connected to,the pumpdelivery space I) and with theoverflow valve of the regulating device e. The valve J is'moved againstthe pressure of a strong spring P, so dimensioned as'to 4 additional tothe load derived from the maintainthe valve J closed against the highestfluid pressure arising beneath it.

The delivery valve H is fitted in a screwthreaded body M which bearsupon the piston guide K and is closed at the top by a cap N. The controlvalve J moves in a guide member 0 which is tightly screwed into the capN. The height of opening of the control valve J can be determined by thethickness of a packing T.

In place of a control valve J of the form illustrated, a ground slidevalve may be employed.

In each of the constructions described, since the loading of theoverflow valve is derived from the pressure diiierential hereinbeforereferred to, the connections for utilising that energy can be made infront of or behind the air throttle. Similarly, the injection nozzle,when fitted in front of the air inlet valve, can be inserted at anyposition in the suction passage in front of or behind the air throttle.

As has already been pointed out, it may be necessary or desirable tocorrect the proportions of the mixture to take account of differentcircumstances. Thus, it may be found that the quantity of fuel at higherengine speeds becomes too great as a consequence of the air attenuationthen taking place, so that the mixture becomes too rich. This dificultyis met by the provision of the spring g illustrated in Figures 1 and 3,which acts to apply an approximately constant load to the overflow valve71. ressure of the air how. The effect of such a ditional load can beseen from Figure 6, in which the addition of the load pe produces thefinal fuel pressure curve indicated by the broken line C', D'. By takingthe square rootsof the values given for the pressure (p+pe) by the curveC, D, the curve G, H is obtained which, as can be seen from thedrawings, has a downward concavity, in contradistinction to the straightline curve E, F. that is, the rate of increase of the fuel injectionvelocity is not directly proportional to the engine speed but decreasessomewhat as the engine speed increases. It is easy by the choice of aspring of appropriate strength so to adjust this relative decrease ofthe fuel injection velocity as to permit the maintenance of a mixture ofuniform proportions at all engine speeds.

Figure 7 illustrates a case in which the mixture proportions arecorrected so that the mixture is richer-with light and full load thanwith intermediate loads, as may be required, for example, in an aircraftengine. In theflgure the continuous curve 1 represents the variations ofair pressure behind the throttle and, consequently, of the rection isapplied, said curve b being proportional.

- to the curve 1 The supply should, however, comply with the curve b'-,that is to say, the mixture should be richer with no'load and with fullload than with intermediate loads. r

This may be achieved, for example, by the apparatus illustrated inFigure 11, which comprises a regulator 9, operating similarly to theregulator illustrated inFlgure 1, and having an overflow needle h loadedby a diaphragm f, the upper side of which is connected'to a region ofhigh-pressure in the air supply passage, while the lower side thereof isconnected to a region of lower pressure. The said diaphragm j is furtherloaded by a spring 9, the-upper abutment of which is formed by thedisplaceable piston in the casing cover e The piston g is displaced by acam disc 9 v and the spring g is tensioned as soon as the cam disc,which is connected to the throttle valve A- the cam disc g by means of apiston which is loaded on one side by the pressure of the air supply infront of the throttle and on the other side the-throttle.

Figure 8 illustrates a correction whichis suitable, for example, for theengines of heavy motor vehicles. In this case, the additional output andconsequently the increase in the supply is provided, as indicated at bat a road speed at which gear-changing takes place after which a rapidincrease in the torque is necessary. The correction indicated in Figure8 may be obtained by means of the apparatus illustrated in Figure 12which comprises a centrifugal regulator g which actuates a cam disc othrough a lever g and connecting rod g in a manner similar to thatillustratedin Figure'll. When the regulator g rises owing toan increasein the speed, the cam disc 9 is thereby displaced to the left and soreduces the spring tension. When the regulator 9 descends, the camincreases the tension of the spring and consequently the supply of fuel.

If the engine is to be used at considerably varying altitudes it isdesirable to effect acorrection to compensate for the change in the airdensity, the reduction of which from a, very low altitude up to analtitude of 12 kilometres is indicated by the curve I in Figure 9. Thereduction in pressure of the fuel supply, however, follows the curve 12if no correction is applied, and thus differs in creasingly from the airpressure with increasing altitude. The present invention provides acorrection of the fuel pressure whereby the curve 1) is obtained, whichprovides a sufficient approximation of the fuel pressure variation tothe air density variation.

as is indicated in Figure 9. If, at this point, the

, action of the diaphragm chamber e is replaced by that of a smallpiston which is loaded-on one side by the external air pressure and onthe other side by the pressure of the air supply, an effect can beobtained which is similar to that produced by the diaphragm chamber fillustrated in Figure.

13, so that the fuel curve b is corrected at its right hand end to theform of the curve b. This result is obtained if the correcting -pistonis rendered operative, for. example by means of the regulator of thesupercharger, only when the by a spring and by the negative pressurebehind given maximum altitude of 6 kilometres has been exceeded.However, it is advantageous for this correction also to be renderedeffective before the said altitude has been attained as is indicated inFigure 10. This is due to the fact that-if the air supply pressure ismaintained constant up to the said maximum altitude, the quantity offresh air charged does not remain constant, but is in creased by anamount varying from approximately 20% until the said altitude isreached, owing to the influence of residual gas and temperature. Byapplying the correction referred to, however, the air supply pressurecurve and the fuel supply curve are corrected to the form of the curve Iand the left hand end of the curve b.

Since the differential pressure increases when descending from the saidmaximum altitude, that is to say from 6 kilometres in this case, thearrangement also produces the correction when deeeending from thataltitude.

An apparatus suitable for effecting the correcuon illustrated in Figure10 is illustrated in Figure 14, in which a piston B and spring B, whichare both enclosed in a cylinder B act.on a regulator diaphragm Lsuch asis illustrated in Figure 11,

' through a connecting red C.

. A device suitable for this correction is illustrated in Figure 13, inwhich a diaphragm chamber f is mounted on the cover e of a regulatorcasing e of the form already described, the said diaphragm chamber facting, through a lever f and a connecting rod f on the regulatordiaphragm and expanding with increasing altitude,

' due'to the decreasing air density, so as to reduce the load on saidregulator diaphragm.

portion as the external air pressure, as indicated by curve I. Thedevice illustrated in Figure 1 of the drawings would provide a mixtureof the correct proportions up to the said maximum altitude, (curve I1and b but as indicated by the curve b would then produce the samedeviation The space above the piston B communicates through a passage Bwith the space above the regulator diaphragm f and thus with the airsuption illustrated by Figure 7 may be employed,

simultaneously with the altitude correction illustrated by Figure 10. Insuch a case, in addition to the piston B loaded with the differentialpressure, there would be a, spring of variable tension acting on theregulator diaphragm and controlled as in Figure 11. Alternatively thetension of the spring B below the piston B would be controlled toproduce the correction indicated in Figure 7.

. supply decreases substantially in the same pro- 1 I claim:

1. Apparatus for supplying fuel and air to an.

internal combustion engine comprising in combination an air passagealong which air flows to let connected to said injection nozzle 'forsupplying fuel thereto at a rate which is in excess of that required fornormal operation of said engine; a control valve connected between theoutlet of said pump and said source of fuel, said 1 valve, when closed,causing complete delivery of fuel from said pump to said injectionnozzle and, when open, causing the return from the outlet of said pumpto the source of fuel of the amount of fuel in excess of that requiredfor the operation of the engine; and actuating means for said controlvalve comprising a closed casing, and a pressure responsive deviceconnected to said valve and positioned within said casing between theupper and lower ends thereof to define upper and lower chambers withinsaid casing, said upper chamber communicating with said air passage at apoint in advance of the apertured constric- 1 tion therein and saidlower chamber communicating with the apertured constriction, oppositesides of said pressure responsive device being acted upon by pressuresderived from the motion of air along the air passage in advance of thethrottle valve within said passage, the resultant of which pressures isdirectly proportional in magnitude to the rate of flow of said airwhereby the valve is opened and closed in accordance with pressuredifierentials derived from the motion of the air along theair passage inadvance of the throttle valve therein.

2. Apparatus for supplying fuel and air to an internal combustion engineas specified in claim 1, wherein the engine is of the multiple cylindertype and wherein the pump comprises a multiple piston pump, the pistonsof which correspond respectively to the number of injection nozzles,there being a. pressure chamber incorporated in the pump into which allof the pistons thereof discharge, a connection between the pressurechamber and each of the nozzles, and control means operated by each ofthe pistons of the pump during the discharge stroke of the piston toopen the connection to the corresponding nomle.

3. Apparatus for supplying fuel and air to an internal combustion engineas specified in claim 1, wherein the engine is of the multiple cylindertype and wherein the pump comprises a multiple piston pump, the pistonsof which correspond respectively to the number of injection nozzles,there being a pressure chamber incorporated in the pump into which allof the pistons thereof discharge, a discharge valve for each pumpcylinder co-operating with the piston therein and positively openedthereby during the discharge stroke, and a control valve co-operatingwith each discharge valve and operated thereby when the discharge valveis opened by the piston, so as to provide communication between thepressure chamher and the corresponding nozzle.

5.Apparatus forsupplying fuel and air to an internal combustion engineas specified in claim 1, wherein the control valve is movable under theeiTect of a. force additional to that derived from the pressurediiierential exercised upon the pressure-responsive device, whichadditional force is exercised by a spring having means for varyingautomatically in accordance with a predetermined condition arisingduring operation of the engine incorporating the apparatus, the force itapplies to the control valve.

6. Apparatus for supplying fuel and air to an internal combustion engineas specified in claim 1, wherein the control valve is movable under theeffect of a force additional to that derived from the pressuredifferential exercised upon the preston pump, the pistons or whichcorrespond reher-and each of the nozzles, and control means operated byeach of the pistonsof the pump during the discharge stroke of the pistonto open the connection to the corresponding nozzle, and

the arrangement being such that each piston of the pump is caused toreach the end of its discharge stroke at the mid-point of the injectionperiod of the corresponding-nozzle.

4. Apparatus for supplying fuel and air to an internal combustion engineas specified in claim 1,

wherein the engine is of the multiple cylinder typ and wherein the pumpcomprises a multiple pissure-responsive device, which additional forceis exercised by a spring having means for varying in accordance with theopening \of a throttle in the air passage, the force it' applies to thecontrol valve.

'1. Apparatus for supplying fuel and air to an internal combustionengine as specified in claim 1, wherein the control valve is movableunder the effect of a force additional to that derived from the pressuredifferential exercised upon the pressure-responsive device, whichadditional force is exercised by a spring having means for adjusting itstension, the adjusting 'means for the spring being operatively connectedto a throttle valve in the air passage so as to be operatedsimultaneously therewith.

8. Apparatus for supplying fuel and air to an internal combustion engineas specified in claim 1, wherein the control valve is movable under theefiect of a force additional to that derived from the pressurediflferential exercised upon the pressure-responsive device, means beingprovided for varying the said additional force in accordance withvariations in the altitude at which the engine sure-responsive device,-means being provided for varying the said additional force in accordancewith variations in the altitude at which the engine incorporating theapparatus is-operatlng. which means comprises a barometric capsule,

PROSPER L'ORANGE.

